EFFECT OF SUGARCANE MULCH THICKNESS ON EMERGENCE OF FOUR VINE SPECIES: RESULTS OF A POT TRIAL

THE IMPACT OF different thicknesses of cane trash blanket on the emergence of four common vine species in sugarcane fields (pink convolvulus – Ipomoea triloba, red convolvulus – I. hederifolia, siratro – Macroptilium atropurpureum and centro – Centrosema molle) was investigated in a pot trial in Mackay, Queensland. The experiment also compared the effect of trash blanket versus inert mulch to assess if allelopathic compounds impact on vine germination. A high level of trash (equivalent to 18 t/ha) reduced the final number of emerged vine seedlings by 66% on average compared to a low level of trash (6 t/ha) and bare soil. A medium level of trash (12 t/ha) reduced seedling emergence by 32% on average compared to bare soil whereas a low level of trash did not reduce vine emergence. Mulching affected the emergence of the tested vine species differently. With 78% emergence, siratro was less impacted by the mulch treatments than red convolvulus and centro (60 and 66% emergence respectively). Hypocotyls were proportionally longer with increase in trash level. Hypocotyl elongation/ trash level ratio was higher for Ipomoeas than legumes, suggesting a higher plasticity of Ipomoeas that would allow them to grow through even thicker trash. This experiment was unable to confirm the hypothesis of an allelopathic effect of cane trash on the tested vine species and seemed to indicate the physical barrier of the trash was the predominant parameter that impeded on vine emergence.